Abstract
Several bacterial response regulator proteins (CheY, NRI, PhoB, and OmpR) become phosphorylated in vitro when incubated with acetyl phosphate. In the presence of high levels of acetyl phosphate and Mg2+, CheY reached steady state phosphorylation in less than 30 s; NRI and PhoB reached steady state more slowly (t1/2 to steady state of 1.5 and > 15 min, respectively). A simple method was developed to measure acetyl phosphate levels in Escherichia coli grown in defined media. Levels of acetyl phosphate were elevated in cells grown in pyruvate, glucose, and glucuronic acid and were low in cells grown in fructose, glycerol, and fumarate. The effects of varying the intracellular amounts of acetyl phosphate on chemotaxis and the osmo-response were also investigated. Acetyl phosphate was not required but did influence each of these responses. These results suggest that acetyl phosphate may influence either the sensitivity or the magnitude of an adaptive response.
Highlights
NR, and PhoB reached steady state more slowly
Phosphorylation of Response Regulators by Acetyl Phosphate-We previously reported that CheY and NR, are mixed and allowed to sit on ice for 30 min
In this paperwe have furthered our initial findings regarding the activation of response regulators by acetyl phosphate
Summary
Vol 269, No 50, Issue of December 16, pp. 3156731572, 1994 Printed in U.S.A. William R. - steady state of 1.5 and >15 min, respectively).A simple The intracellular poolof acetyl phosphate is controlled by method was developed to measure acetyl phosphate letwv-o reactions, catalyzed by acetate kinase and phosphotransvveagogalnaacrsettroceeitywnhyd,innle.EgmgiplAsnuchotcchhotefoeaerstsryxupeiilincch,sthtapoaritahsanaeneocdc,dsweoplggllehiutllryhuaglecaetcreerueorolraowwesolmvnm,anasioiaontcuen-ndrndaodetctesisinfpfdruoionefmcnqaeeaudasnlcleridsgeramrtewtywdeoeale.weldrpbrnsTeihuoeahiot.nielnsodLpvpweiheedyfvsafrtieooetiunicneffl-s-tfscluetC+ae-lhcnloAseAeAeetTrEcygxPeKlittaer,y[,sasKlec=ope,efrgh9le=lh.os2uysp61lpdea6xrhcr1otpa1iltvhy.eeos,lisysap.ca(hen11atd2y)ta)el2.-cac)eUnaotdycnAeltd-,htecyaerolntAgopdrth+oaAolwPTsinpt,Phthraacaltoaclecne+hedllatAiuytviDlleoapnPrhssi*omisnpailhcwaearhCttiaefocrtAh+eee ence eachof these responses. These results suggest thactoncentrationsremainconstant,andin which theenergy acetyl phosphate may influence either the sensitivity ocrharge inATP (and ADP) remains constant, the main determithe magnitude of an adaptive response. When either acetyl-coA or acetate accumulates the level of acetyl phosphate increases. One would predict that a mutant that is ablatedfor a particular sensory kinase would be blind to the signals that that sensordetects.
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